Fuel Cell for Use in an Alcohol Breath Tester

ABSTRACT

An improved alcohol fuel cell sensor and alcohol breath tester assembly where wires for connection to the electrodes are bent to have a generally planar base portion which may be positioned toward the center of the electrodes and an upright that then extends to the outside of the case. The uprights are generally perpendicular to the base allowing the wires to exit the housing toward the center, as opposed to toward an edge.

CROSS REFERENCE TO RELATED APPLICATION(S)

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 61/677,081, filed Jul. 30, 2012, the entiredisclosure of which is herein incorporated by reference.

BACKGROUND

1. Field of the Invention

This disclosure relates generally to devices for estimating bloodalcohol content from a breath sample, and more particularly, to fuelcells for use in estimating blood alcohol content from a breath sample.

2. Description of the Related Art

An alcoholic beverage is a drink containing ethanol, commonly known asalcohol, although in chemistry the definition of alcohol includes manyother compounds. Alcohol, specifically ethanol, is a psychoactive drugand is a powerful central nervous system depressant with a range of sideeffects.

Alcohol has a biphasic effect on the body, which is to say that itseffects change over time. In the initial stages of intoxication, alcoholgenerally produces feelings of relaxation and cheerfulness. Furtherconsumption however affects the brain leading to slurred speech, blurredvision, clumsiness and delayed reflexes, among other coordinationproblems. This condition is commonly referred to as intoxication ordrunkenness, and eventually subsides when the alcohol has fullymetabolized in the body.

When a human drinks alcohol, the alcohol housed in the stomach passesinto the bloodstream. Cell membranes are highly permeable to alcohol, soonce alcohol is in the bloodstream it can diffuse into nearly everybiological tissue of the body. Once in the bloodstream, the alcoholcirculates to the brain, resulting in intoxication, loss of inhibitionand impairment of motor skills such as driving a vehicle. The amount ofalcohol consumed and the circumstances surrounding consumption play alarge role in determining the extent of an individual's intoxication.Examples of such circumstances include the amount of food in the stomachat the time of alcohol consumption and the hydration level of theindividual at the time of consumption, among others.

Due to the coordination impairment and other symptoms associated withintoxication and drunkenness, most countries have laws against drunkdriving, i.e., driving with a certain concentration of ethanol in theblood. The legal threshold of blood alcohol content ranges from 0.0% to0.08%, depending on the jurisdiction. Punishments for operating avehicle over the legal limit in a given jurisdiction generally includefines, temporary loss of an individual's driving license andimprisonment. Creation of these laws has led to a market for devices toaccurately measure the blood alcohol content of individuals operatingmotor vehicles.

Blood alcohol content (BAC) or blood alcohol concentration is theconcentration of alcohol in the blood (weight per unit volume). Whileblood alcohol content can be directly measured in a hospital laboratorysetting, it is more common for it to be measured in law enforcementsituations by estimation from an individual's breath alcoholconcentration using a breath alcohol testing machine.

In the world of alcohol-breath testing and related fields of alcoholtesting, one of the most common configurations uses fuel cells asalcohol sensors, with the assembly allowing breath, air, gas, or vaporto be passed into the fuel cell. In its simplest form, the alcohol fuelcell is a wafer consisting of a chemically inert porous material coatedon both sides with thin layers of catalyst such as platinum (formingupper and lower platinum electrode layers.) The porous materialsandwiched between the two platinum layers contains a liquidacid-electrolyte. The electrolyte allows charges to move between the twoelectrode layers of the wafer. Those skilled in the art would understandthat the chemically inert porous material, filled with a liquidacid-electrolyte, could be replaced by, under certain circumstances, asolid electrolyte element.

Round, platinum wire electrical connections are then applied to theplatinum electrodes and connected to an external circuit. In thisregard, the wafer is generally a solid, planar shape allowing for wireto electrode connections at any point on the wafer. The entire fuel cellsensor is mounted in a plastic case, which is provided with a gas inletthat allows a breath sample to be introduced into the assembly. Thebasic configuration is as described above, and illustrated in FIG. 1.

In the fuel cell sensor, the top platinum electrode (the one closest tothe gas inlet) oxidizes any alcohol in the breath sample to produceacetic acid in a 2 step process (ethanol→acetaldehyde→acetic acid) andwhich also produces free electrons in the process. Hydrogen ions (H+)are also freed in the process, and migrate to the lower platinumelectrode of the cell, where they combine with atmospheric oxygen toform water, resulting in a deficiency of electrons on the lowerelectrode equal to the excess of electrons produced on the uppersurface. Because the two electrode surfaces are connected electrically,a current flows through this external circuit to neutralize the charge.With suitable amplification, this current is a precise indicator of theamount of alcohol consumed by the fuel cell, as the number of electronsproduced is directly and linearly proportional to the number of alcoholmolecules arriving at the catalyst surface. With the number of alcoholmolecules, the blood alcohol content can then be determined. Thisprocess is illustrated in FIG. 2.

For the fuel cell sensor to operate properly, the wires connecting theelectrodes must have a low ohm connection with the platinum electrodeson the wafer. Otherwise, a high resistance connection hinders theoperation of the fuel cell and makes it less accurate and slower. The“wires” can take on a variety of forms, but as noted above, round, solidplatinum wires are the most common. They are generally considered thebest, most readily available, and most versatile. Other forms can beused besides round wire, such as wire mesh or flat ribbon. Additionally,other materials can be used besides platinum, such as gold or platedmaterials, but resistance to the harsh acidic environment of a fuel cellcan limit the number of choices of conductors. In any event, the wireshould not disrupt the thin layer of platinum, and should take intoconsideration the well understood effects of dissimilar metal junctions.

As noted herein, it is common practice by those skilled in the art touse small round platinum wires. platinum, however, is an expensivecommodity, so using as little wire as possible can be importanteconomically. The platinum wire only needs to contact a portion of theplatinum surface. Thus, at times, the platinum wires are transitioned tosome other, more economical conductor once the wires have exited theharsh acidic environment inside the fuel cell case/assembly.

Moreover, there exists a considerable price pressure in the marketplacefor alcohol fuel cell sensors, specifically in the breath-testing field.Most manufacturers use low cost and simple components in theconstruction of such fuel cell sensor assemblies. Added complexity ofdesign can result in higher costs for tooling, parts, and labor. For allthese reasons, a common simple construction assembly used by manymanufacturers can be generally described as follows and as illustratedin FIG. 3: a first wire (a) is added to a lower plastic case (b); aplatinum coated disk (c) is added on top of the first wire (a) and case(b); a second wire (d) is added over the disk (c); and a upper plasticcover (e) is added to seal the assembly.

It is important that the assembly be sealed for a couple of reasons.First, it ensures that no electrolyte can leak out of the assembly.Second, gas can only enter the assembly through the inlet. For sealing,manufacturers use glues, epoxies, ultrasonic welding, flexible seals,and other types of sealing methods known to those skilled in the art. Inorder for the assembly to be fully sealed, the case halves must besealed together, the wires must be sealed to the case, and the peripheryof the disk must be sealed to the inside of the case half.

Importantly, the wires must have good contact with the platinum surfaceof the electrodes. This contact is most easily accomplished by aclamping force that “squeezes” the platinum disk between the wires—oftenthe platinum wires can actually compress the platinum electrodes andembed in that surface to some degree. Additionally, this contact andforce needs to be maintained throughout the life of the sensor.

As shown in FIG. 3, with many of the prior art assemblies, as the wiresare added to the assembly, some of the parts in the assembly becomecanted. Not only does this make the assembly more difficult, but thewires may lose contact with the platinum electrode surface over time,resulting in non-functionality of the fuel cell.

There have been attempts in the prior art to ensure this contact, butthey all have their own problems. As shown in FIG. 4, one option is toadd spacers or compensating elements in areas where the wires are notpresent. This design, however, is much more complicated and requires acritical equivalence between the dimensions of the compensating elementsand the platinum wire in order to properly function. Additionally, thisdesign results in difficulties in maintaining the same clamping forceacross a batch of assemblies, with some of the manufactured assembliesinevitably clamping the platinum wire to the electrode surface betterthan others. Although the compensating elements could be spring-loadedin some form to improve the design to ensure proper and even clampingforce, such spring-loading only complicates the assembly even further.

A second option is to shape the wires into loops (or portions of loops)that encircle the circumference of the wafer or to span the entirelength or diameter of the wafer, as shown in FIG. 5. This is a morereliable option (if used with the proper clamping force) in that itprovides more assurance that the platinum wire will remain in contactwith the electrode surface, as the housing clamps the outside of thewafer and locks the wires into place. However, the circumferential loopsand/or lengthened wire require much more platinum wire which addssignificant expense to the assembly.

In summary, fuel cell assemblies generally require some type of wire(e.g., platinum wire) to be attached to platinum electrodes in a secure,low resistance manner. One type of assembly uses a permanent clampingforce to hold the electrodes and wires in close electrical contact, withthe expensive wires generally spanning nearly the entire length,diameter, or circumference of the wafer. The other requirements of theassembly (such as simplicity of parts, sealing, low cost, and ease ofassembly), however, can result in a design with significant risk in thereliability of the internal electrical connection. The largest risk isthat a less than optimal electrical connection made during the assemblyprocess may only manifest itself later during field use, resulting in anon-functional breath tester.

SUMMARY

In view of the above described and other problems in the art, disclosedherein is an improved alcohol fuel cell sensor and alcohol breath testerassembly where wires for connection to the electrodes are bent to have agenerally planar base portion which may be positioned toward the centerof the electrodes and an upright that then extends to the outside of thecase. The uprights are generally perpendicular to the base allowing thewires to exit the housing toward the center, as opposed to toward anedge. The resultant assembly incorporates a contact force between thewires and platinum electrode while insuring an electrical contactbetween the platinum electrode and wires that last over a significantperiod of time. This results in a design that is reliable in the field.Further, the disclosed cell does this by means independent of otherassembly steps required to make a complete alcohol breath testerassembly, and by using minimum amounts of platinum wire, resulting in aless expensive yet reliable fuel cell.

The disclosed fuel cell sensor and assembly can have further advantagesover the state of the art: (1) it can be easily incorporated into a vastvariety of independent housing designs that otherwise need not addressthe integrity of the internal electrical connection; (2) it is scalable,and, thus, not restricted to any particular size or shape of fuel cell;(3) the fuel cell may be incorporated as an independent sub-assembly orin concert with the fuel cell case in some customized manner; (4) thefuel cell can be very simply incorporated into a printed circuit boardassembly in a robust and economical manner; (5) the fuel cell allows forincorporation of a second wafer (such as an electrolyte reservoirwafer).

There is described herein, among other things, a fuel cell sensorcomprising: a generally flat wafer having: two opposing major surfaces;and an electrode on each of the two opposing major surfaces; theelectrode extending to an outer periphery; and a plurality of elongatedwires having a major dimension, each of the wires including: a baseportion; and an upright; wherein the base portion is arranged to be allof the following: non-linear in the major dimension; generally planarwithin a perimeter; and the perimeter being smaller than the outerperiphery; and wherein the upright is generally linear in the majordimension; wherein the base portion of a first of the plurality ofelongated wires is arranged parallel to and in contact with a first ofthe electrodes; and wherein the base portion of a second of theplurality of elongated wires is arranged parallel to and in contact witha second of the electrodes.

In an embodiment of the fuel cell, the generally flat wafer includes ahole.

In an embodiment of the fuel cell, the base portion and the upright arearranged so that the upright is generally orthogonal to the plane of thebase portion.

In an embodiment of the fuel cell, the upright of the first of theplurality of elongated wires extends through the hole and the upright ofthe second of the plurality of elongated wires is above the hole.

In an embodiment the fuel cell further comprises a clamping pin, theclamping pin including: a pin base, the pin base being adjacent to thebase portion of the first of the elongated wires; and a column, thecolumn extending through the hole.

In an embodiment of the fuel cell, the column further includes: a firstgroove through which the upright of the first of the plurality ofelongated wires extends; and a second groove through which the uprightof the second of the plurality of elongated wires extends.

In an embodiment of the fuel cell, the base further includes a groovecorresponding to the base portion of the first of the elongated wires.

In an embodiment the fuel cell further comprises a sleeve, the sleeveincluding a central opening corresponding in size and shape to thecolumn so that the sleeve can fit over the column.

In an embodiment of the fuel cell, the sleeve includes a geometric tabfeature, the geometric tab feature mating with the slot on the clampingpin.

In an embodiment of the fuel cell, the hole passes through the center ofthe electrodes.

In an embodiment of the fuel cell, the fuel cell is enclosed in ahousing having an upper portion and a lower portion, the upper portionincluding a central hole, and both the upright of the first of theplurality of elongated wires and the upright of the second of theplurality of elongated wires extend through the hole in the upperportion.

In an embodiment of the fuel cell, the base portion of the first of theplurality of elongated wires is closer to the lower portion than theupper portion and the base of the second of the plurality of elongatedwires is closer to the upper portion than the lower portion.

In an embodiment of the fuel cell, a gas sample is supplied through agas intake port in the lower portion.

In an embodiment of the fuel cell, the electrodes comprise platinum.

In an embodiment of the fuel cell, the wires comprise platinum.

In an embodiment of the fuel cell, the wires are selected from the groupconsisting of: round wires and wire ribbons.

In an embodiment of the fuel cell, the base portion and the upright arearranged so that the upright is generally co-planar to the plane of thebase portion.

There is also described herein, a fuel cell sensor comprising: agenerally flat wafer having: two opposing major surfaces; and anelectrode on each of the two opposing major surfaces the electrodeextending to an outer periphery; and a plurality of flex circuits, eachof the flex circuits including: a generally planar base portion having aperimeter; and an upright; wherein the perimeter is smaller than theouter periphery; and wherein the upright extends generally linearly fromthe base portion; wherein the base portion of a first of the pluralityof flex circuits is arranged parallel to and in contact with a first ofthe electrodes; and wherein the base portion of a second of theplurality of flex circuits is arranged parallel to and in contact with asecond of the electrodes.

In an embodiment of the fuel cell, the plurality of flex circuitsinclude selective gold plating on all or part of the planar portion,such plating providing an electrical connection to the electrode.

In an embodiment of the fuel cell, the plurality of flex circuitsinclude selective gold plating; such plating being thicker than theremainder of the flex circuit.

In an embodiment of the fuel cell, the plurality of flex circuits haveat least a portion which is acid-resistant.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a basic configuration of an embodiment of a fuel cellsensor and assembly of the prior art.

FIG. 2 depicts the embodiment of FIG. 1 and showing the chemicalreaction and current flow as alcohol from a breath sample is introducedinto the assembly.

FIG. 3 depicts the canted nature of the assembly and fuel cell thatcommonly results from the basic configuration of the prior art.

FIG. 4 depicts the assembly of FIG. 3 with compensating elements addedto correct the canted nature of the assembly.

FIG. 5 depicts the assembly of FIG. 3 with the wires shaped in largeloops around the periphery of the wafer to correct the canted nature ofthe assembly.

FIG. 6A is a side view of an embodiment of a fuel cell with a sleevebeing utilized.

FIG. 6B is a cross-sectional side view of the embodiment of FIG. 6A.

FIG. 6C is a perspective view of the fuel cell of FIG. 6A.

FIG. 7A is a side view of an embodiment of a fuel cell without a sleevebeing utilized.

FIG. 7B is a cross-sectional side view of the embodiment of FIG. 7A.

FIG. 7C is a perspective view of the embodiment of FIG. 7A.

FIG. 8 is a perspective view of an embodiment of an assembly with thefuel cell shown in FIG. 7C combined with a lower housing and upperhousing.

FIG. 9 is a perspective view of the embodiment of FIG. 8, with theassembly being connected to a circuit board.

FIG. 10A is a side view of an embodiment of a fuel cell where thecentrally clamped wires exit the fuel cell in the conventional manner onthe side.

FIG. 10B is a top down view of the embodiment of FIG. 10A.

FIG. 10C is a side view of the embodiment of FIG. 10A with the clampingpin and sleeve in place.

FIG. 10D is a top down view of the embodiment of FIG. 10C.

FIG. 11A is a side view of a fuel cell embodiment where the centrallyclamped wires are replaced with a flexible circuit.

FIG. 11B is a top down view of the embodiment of FIG. 11A.

FIG. 11C is a side view of a fuel cell embodiment where the centrallyclamped wires are replaced with a flexible circuit that is thicker thanthe embodiment of FIG. 11A.

FIG. 11D is a top down view of the embodiment of FIG. 11C

FIG. 11E is a side view of the embodiment of FIG. 11A with the clampingpin and sleeve in place.

FIG. 11F is a top down view of the embodiment of FIG. 11E.

DESCRIPTION OF PREFERRED EMBODIMENT(S)

Turning now to FIGS. 6-9, the disclosed fuel cell (100), and resultantassembly (101), will be described in greater detail. Generally, the fuelcell (100) will comprise a platinum wafer (200), a clamping pin (110),and two wires (150). As discussed more fully below, the wafer (200) issimilar to the prior art wafers excepting that the wafer (200) has aninterior hole (201) within which the clamping pin (110) is mounted, withthe clamping pin (110) housing the wires and creating a permanent forcefor connecting the wires (150) to the wafer (200).

With the interior hole (201) and the clamping pin (110), it is notnecessary, as in the prior art, for the wires (150) to span the lengthor diameter of the wafer (200) or for the wires (150) to exit on theside of the wafer (200). Instead, the wires (150) are able connect toand extend from the wafer (200) at or near the center of the wafer(200). The fuel cell (100) can then be enclosed in various types ofhousing (700) with the wires (150) positioned towards the center (asopposed to the periphery) of the housing (700) while still maintainingsufficient contact with the wafer (200). An example is a case (700) thatcreates an alcohol breath tester assembly (101) which allows gas/breathto enter the assembly (101) through a gas intake port (173).

As noted above, the wafer (200), or a combination of wafers, generallycomprises a chemically inert center material (205) such as, but notlimited to, Polyvinyl Chloride or Polypropylene coated on both sides toa periphery (202) at or around the outside edge of the inert centermaterial (205) with thin layers of platinum (forming upper and lowerplatinum electrode layers (203) and (204)). An acid-electrolyte materialsuch as sulfuric or phosphoric acid fills the pores of the inert centerlayer (205) sandwiched between the two electrode layers (203) and (204).The electrolyte allows charges to move between the two electrode layers(203) and (204). The wafer (200) generally has a defined shape as wellas a defined hole (201) away from the periphery (202) and generally inthe center of the wafer (200). The wafer (200) can be any shape,including, for example, triangles, rectangles, squares, trapezoids,hexagons, ovals, and the like. A preferred embodiment is a roundelectrode wafer (200) with a round, central hole (201) as shown in FIGS.6 and 7.

As noted above, wires (150) are applied to both electrodes (203) and(204) of the wafer (200) in order to connect with an external circuit.One wire (150 b) is securely applied to the upper electrode layer (203)and the other wire (150 a) is securely applied to the lower electrodelayer (204). Although by no means necessary, a preferred embodiment usestwo wires (150) of substantially identical design and length to simplifyelectrical connections. Thus, components of each wire (150 a) and (150b) are referred to together in this disclosure without use of a letterwhen logical to refer to features common to both with the letter “a”being used to refer to components of the lower wire (150 a) whenappropriate and the letter “b” being used to refer to components of theupper wire (150 b) when appropriate.

The wires (150) are generally elongated round, platinum wires, althoughother suitable metals could be utilized, including, for example, gold orplated materials, and other types could be utilized, including, forexample, wire mesh or flat ribbon. Further, the wires may be replaced byflex circuits (651) as shown in FIG. 11 or by other structures havingsimilar shape as understood by those of ordinary skill.

The wires (150) are generally bent and configured such that theycomprise a base portion (151) where the wire (150) is bent to be anon-linear but generally planar shape (e.g. a polygon or circle) andhaving a perimeter smaller than the periphery (202) of the wafer (200)but no smaller than the exterior dimension of the hole (201). The wires(150) also comprise a leg (152) extending inward toward the center ofthe base portion (151) and along the same plane as the base portion(151), and an upright (153). In the embodiment of FIGS. 6-9, the upright(153) extends substantially perpendicular to the base portion (151) andleg (152). In the embodiment of FIGS. 10 and 11, the upright extendsgenerally co-planar with the base portion (151) The base portion (151 b)and leg (152 b) of the wire (150 b) are the parts applied in electricalcontact with the upper platinum layer (203), with the base portion (151a) and leg (152 a) of the wire (150 a) being applied in electricalcontact with and the lower platinum layer (204). The clamping pin (110)then securely holds the wire (150 a) in place on the wafer (200) withthe clamping pin (110), a sleeve (120), and/or the upper housing (170)holding the wire (150 b) in place, as discussed below.

Because the base portion (151) stays clear of the periphery (202) of theelectrode (203) or (204) and is generally around the center of the wafer(200), a smaller amount of wire (150) (and, thus, platinum when platinumis used) is required than designs which cross the wafer (200) orsurround the electrode (203) or (204) toward the periphery (202) (suchas that shown in FIG. 5). Additionally, a variety of case (700) designscan be utilized to easily seal the wafer (200) around its edges in theresultant assembly (101), for example, the upper housing (170) and lowerhousing (171) shown in FIG. 8 and discussed below.

As noted above, the clamping pin (110) secures the wires (150) to thewafer (200) and ensures that an electrical connection is maintained. Assuch, the clamping pin (110) is generally securely mounted in and aboutthe interior hole (201) of the electrode wafer (201), as shown in FIGS.6 and 7. In an embodiment, the clamping pin (110) comprises a pin base(111) and a column (112) extending from the center of the pin base(111). The base may include a groove (115) between the outside of thepin base (111) and the column (112), with the groove (115) sized andshaped for receiving the base portion (151 a) of one of the wires (150a), as discussed below. In the depicted embodiment, both the pin base(111) and column (112) are circular to match the shape of the hole (201)in the wafer (200) with the outer diameter of the column (112)approximately equal to the inner diameter of the wafer hole (201) inorder to securely and snugly mount the pin (110) in the hole (201).

As noted above, however, the hole (201) and wafer (200) may be anyshape, and as a result, the column (112) and pin base (111) similarlymay be any shape and will generally be a complimentary shape to the hole(201). Regardless of the shape, the pin (110) is generally able to besecurely placed into the hole (201) in the wafer (200), which allows thewires (150) to be securely and permanently connected to the wafer (200).In other words, a case or housing (700) is not required to insure theintegrity of the electrical connection between the wires (150) and thewafer (200) and the fuel cell sensor (100) may be installed in nearlyany case design. One means for accomplishing this secure connection isto have the column (112) and hole (201) approximately the same size andshape, although this is by no means the only way to have the pin (110)securely placed into the hole (201).

In addition to the groove (115) for receiving the wire (150 a) on thecomplementary side of the wafer (200), the column (112) of the pin (110)will generally also have two slots (113) and (114) for receiving the twowires (150 a) and (150 b), respectively. The first slot (113) willgenerally extend the length of the column (112) such that the slot (113)meets with the groove (115) in order to receive the first wire (150 a).The second slot (114) will generally only extend part of the length ofthe column (112), as the second wire (150 b) will be separated from thegroove (115) by the wafer (200). In any event, the three receiving partsof the clamping pin (110)—the groove (115) and two slots (113) and(114)—generally receive the wires (150) in such a manner that the wires(150) are securely and snugly connected to the pin (110).

The fuel cell (100) may also include a sleeve (120) for further securingthe clamping pin (110), and thus the wires (150), to the wafer (200), asshown in FIGS. 6A-6C. The sleeve (120) is generally a hollowtubular-like structure with the interior passageway sized and shaped tomatch the column (112) of the clamping pin (110). As a result, thesleeve (120) and clamping pin (110) can be held together by slip fit,press fit, and/or snap fit. Additionally, or alternatively, thoseskilled in the art would understand that any variety of methods can beused to hold the two pieces together, including, but not limited to,glue, heat weld, or ultrasonic weld. The sleeve (120) can serve to makea similar flanged structure to the pin base (111) on the opposing sideof the wafer (200) (at electrode (203)) resulting in a similar clampingstructure to both base portions (151) on both wires (150).

The sleeve (120) may also has a geometric tab feature (121) that applieswhen the pin (110) assembly is installed. This tab feature (121) mateswith the slot (113) on the clamping pin (110). This tab feature (121)may act as a barrier to electrically isolate the section of wire (153)from the top platinum layer (203) of the wafer (200) and/or to lock thesleeve (120) and clamping pin (110) together.

As noted, the sleeve (120) is by no means necessary and the wires (150)may be connected with the wafer (200) by merely the clamping pin (110)alone, as shown in FIGS. 7A-7C. Additionally, the sleeve (120) may beincorporated into the upper housing (170) of the assembly (101) tofurther secure the wires (150) to the wafer (200), as suggested in FIG.8. Although a particular case (700) design (i.e., the upper and lowerhousings (170) and (171)) is depicted in FIG. 8, those skilled in theart would readily understand that a variety of case (700) designs couldincorporate the sleeve (120) if desired or needed.

As noted throughout, the fuel cell sensor (100) is enclosed or mountedin some type of case (700) (e.g., a plastic case) to form an assembly(101), with the case being provided with a gas inlet (173) that allows abreath sample to be introduced into the assembly. Advantageously, thefuel cell (100) design allows for use in virtually any type of case(700). As depicted in the embodiment of FIGS. 8-9, the case (700)comprises an upper housing (170) with an outlet (175) for the wires(150) and a lower housing (171) with a gas intake port (173) for thebreath sample and an optional exhaust port (172) for a mechanical meansto move the gas/breath through the fuel cell sensor (100).

The upper housing (170) and a lower housing (171) are then sealedtogether to form the case (700) and, in conjunction with the enclosedfuel cell (200), a fuel cell assembly (101). The sealing ensures that noelectrolyte can leak out of the assembly (101) and that gas can onlyenter the assembly (101) through the gas intake port (173). For sealing,glues, epoxies, ultrasonic welding, flexible seals, press (friction)fits, and other types of sealing methods known to those skilled in theart can be utilized.

Regardless of the type of case (700) utilized and whether or not thesleeve (120) is utilized, due to the hole (201) in the wafer (200), bothwires (150) can exit on the same side of the fuel cell (100) andassembly (101) for easier attachment to, for example, a circuit board(300) or any type of external circuit, and even though the wires (150)each attach to a different side of the wafer (200). Moreover, theattachment to the circuit board (300), or any type of external circuit,can be accomplished with extremely short wires as the wires (150) extendperpendicular to the wafer (200) rather than parallel therewith.

As discussed above, the circuit creates a current within the fuel cell(100) which allows electrons to flow between the upper platinumelectrode layer (203) and the lower platinum electrode layer (204).Additionally, with suitable amplification in the external circuit, thecurrent can be used to determine the amount of alcohol consumed by thefuel cell (100), as the number of electrons produced is directly andlinearly proportional to the number of alcohol molecules arriving at thecatalyst surface.

The fuel cell assembly (101) is generally constructed as follows. First,the base portion (151 a) of the first wire (150 a) is placed in groove(115) of the pin base (111) of the clamping pin (110) with the upright(153 a) and leg (152 a) of the first wire (150 a) being securely placedin the first slot (113). Second, the first wire (150 a) and clamping pin(110) are secured into the hole (201) of the wafer (200) such that baseportion (151 a) of the first wire (150 a) connects with the lowerplatinum electrode layer (204) of the wafer (200) with the upright (153a) of the first wire (150 a) extending through the hole (201). Third,the upright (153 b) and leg (152 b) of the second wire (150 b) aresecurely placed into the second slot (114) of the clamping pin (110)such that base (152 b) of the second wire (150 b) connects with theupper platinum electrode layer (203) of the wafer (200) and the upright(153 b) of the second wire (150 b) extends substantially parallel to thefirst wire (150 a) and is over the hole (201). Finally, the sleeve (120)may optionally be secured over the clamping pin (110), with the tabfeature (121) mating with the first slot (113). A groove in the sleeve(120) may also enclose the base (151 b).

Next, the upper housing (170) is placed over the fuel cell (100) on theside of the upper platinum electrode layer (203) of the wafer (200),with the wires (150) extending through the outlet (175) of the upperhousing (170). The lower housing (171) is then placed over the fuel cellon the side of the lower platinum electrode layer (204) of the wafer(200) and the lower housing (171) and the upper housing (170) are sealedtogether. It will further be appreciated that the outlet (175) of theupper housing (170) merely allows the wires (150) to pass therethroughbut a seal remains such that gas can only enter through the gas intakeport (173) and electrolyte cannot leak out of the outlet (175). Itshould be noted that the case (700) shown in FIG. 8 includes features ofa housing such as that discussed in U.S. patent application Ser. No.13/778,786, the entire disclosure of which is herein incorporated byreference. This arrangement of case (700) can be particularly beneficialwith a fuel cell (100) including centrally discharging wires (151) asthe wire (151 a) does not intersect as much of the gas chamber supplyingthe sample to the wafer (200) in such a housing.

As shown in FIG. 10, in the event that the use of centrally exitingwires as shown in FIGS. 6 and 7 is problematic for the fuel cell (100)case (700) being used, the arrangement of using a base portion (151)inside the periphery of the electrode (203) and (204) may be applied toa wafer (200) to help improve connection to the wafer (200), but themanner of the uprights (153) leaving the wafer (200) may beconventional. In the embodiment of FIG. 10, the wires (150) contain baseportions (151) with a perimeter around the central hole (201) of thewafer (200). As the hole (201) is not used for the uprights (153) thehole may not be present in an alternative embodiment and the perimeterof the base portions (151) may simply surround the center of theelectrodes (203) and (204).

The uprights (153) in FIG. 10 extend generally parallel to the plane ofthe electrodes (203) and (204) and exit the fuel cell housing out theside instead of through the central hole (201). This example takesadvantage of the small central clamping area and the use of clamping pin(110) and sleeve (120) to eliminate a need for spacers and provide goodelectrical connection between wire (150) and electrode (203) and (204).Further, it will provide an assembly where none of the components aregenerally canted avoiding the problem of FIG. 3.

FIG. 11 provides a still further embodiment to that of FIG. 10 (or withthat of FIGS. 6-7) but the coil (150) is replaced with a flex circuit(651). The portion of the flex circuit (651) inside the fuel cellhousing will generally be acid-resistant to resist degradation from theenvironment. This can be accomplished by use of such materials such as,but not limited to, platinum, gold or a polymide such as, but notlimited to, poly(4,4′-oxydiphenylene-pyromellitimide) which is availableunder the trademark Kapton®.

The portion of the flex circuit (651) around the central hole (201),which is indicated by a square patch in FIGS. 11B and 11D (although itmay be any shape), will generally be exposed on only one side so that anelectrical contact may be made between that side and the platinumelectrode (203) or (204). This can minimize the amount of precious metalused in the flex circuit (651) through the use of various techniques,such as, but not limited to, selective gold plating. The remainder ofthe flex circuit (651) can be of more conventional materials, such as,but not limited to copper, in order to save on material costs as long asthese portions are encapsulated in a material, such as those indicatedabove, that is resistant to acid. In an embodiment using a flex circuit(651) it is also possible to eliminate the uprights (153).

As shown in the comparison of FIGS. 11A and 11C, the flex circuit (651)may be all one thickness as shown in FIG. 11A where the central patch(451) is the same thickness as the remainder or may be preferentiallythicker at the central patch (551) around the central hole (201) toprovide more consistent electrical contact. In a still furtherembodiment, the designs of FIGS. 10 and 11 may be combined with one sideof the assembly including a flex circuit (651) and the other sideincluding a wire (150).

While the invention has been described with reference to exemplaryembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from theessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiments disclosed as the best modecontemplated for carrying out this invention, and that the inventionwill include all embodiments falling within the scope of the appendedclaims.

It will further be understood that any of the ranges, values, orcharacteristics given for any single component of the present inventioncan be used interchangeably with any ranges, values, or characteristicsgiven for any of the other components of the invention, wherecompatible, to form an embodiment having defined values for each of thecomponents, as given herein throughout.

1. A fuel cell sensor comprising: a generally flat wafer having: twoopposing major surfaces; and an electrode on each of said two opposingmajor surfaces said electrode extending to an outer periphery; and aplurality of elongated wires having a major dimension, each of saidwires including: a base portion; and an upright; wherein said baseportion is arranged to be all of the following: non-linear in said majordimension; generally planar within a perimeter; and said perimeter beingsmaller than said outer periphery; and wherein said upright is generallylinear in said major dimension; wherein said base portion of a first ofsaid plurality of elongated wires is arranged parallel to and in contactwith a first of said electrodes; and wherein said base portion of asecond of said plurality of elongated wires is arranged parallel to andin contact with a second of said electrodes.
 2. The fuel cell of claim 1wherein said generally flat wafer includes a hole.
 3. The fuel cell ofclaim 2 wherein said base portion and said upright are arranged so thatsaid upright is generally orthogonal to the plane of said base portion.4. The fuel cell of claim 3 wherein said upright of said first of saidplurality of elongated wires extends through said hole and said uprightof said second of said plurality of elongated wires is above said hole.5. The fuel cell of claim 4 further comprising a clamping pin, saidclamping pin including: a pin base, said pin base being adjacent to saidbase portion of said first of said elongated wires; and a column, saidcolumn extending through said hole.
 6. The fuel cell of claim 5 whereinsaid column further includes: a first groove through which said uprightof said first of said plurality of elongated wires extends; and a secondgroove through which said upright of said second of said plurality ofelongated wires extends.
 7. The fuel cell of claim 6 wherein said basefurther includes a groove corresponding to said base portion of saidfirst of said elongated wires.
 8. The fuel cell of claim 7 furthercomprising a sleeve, said sleeve including a central openingcorresponding in size and shape to said column so that said sleeve canfit over said column.
 9. The fuel cell of claim 8 wherein said sleeveincludes a geometric tab feature, said geometric tab feature mating withthe slot on said clamping pin.
 10. The fuel cell of claim 5 wherein saidhole passes through the center of said electrodes.
 11. The fuel cell ofclaim 10 wherein said fuel cell is enclosed in a housing having an upperportion and a lower portion, said upper portion including a centralhole, and both said upright of said first of said plurality of elongatedwires and said upright of said second of said plurality of elongatedwires extend through said hole in said upper portion.
 12. The fuel cellof claim 11 wherein said base portion of said first of said plurality ofelongated wires is closer to said lower portion than said upper portionand said base of said second of said plurality of elongated wires iscloser to said upper portion than said lower portion.
 13. The fuel cellof claim 12 wherein a gas sample is supplied through a gas intake portin said lower portion.
 14. The fuel cell of claim 1 wherein saidelectrodes comprise platinum.
 15. The fuel cell of claim 1 wherein saidwires comprise platinum.
 16. The fuel cell of claim 1 wherein said wiresare selected from the group consisting of: round wires and wire ribbons.17. The fuel cell of claim 1 wherein said base portion and said uprightare arranged so that said upright is generally co-planar to said planeof said base portion.
 18. A fuel cell sensor comprising: a generallyflat wafer having: two opposing major surfaces; and an electrode on eachof said two opposing major surfaces said electrode extending to an outerperiphery; and a plurality of flex circuits, each of said flex circuitsincluding: a generally planar base portion having a perimeter; and anupright; wherein said perimeter is smaller than said outer periphery;and wherein said upright extends generally linearly from said baseportion; wherein said base portion of a first of said plurality of flexcircuits is arranged parallel to and in contact with a first of saidelectrodes; and wherein said base portion of a second of said pluralityof flex circuits is arranged parallel to and in contact with a second ofsaid electrodes.
 19. The fuel cell of claim 18 wherein said plurality offlex circuits include selective gold plating on at least a part of saidplanar portion, said plating providing an electrical connection to saidelectrode.
 20. The fuel cell of claim 18 wherein said plurality of flexcircuits include selective gold plating; said plating being thicker thanthe remainder of said flex circuit.
 21. The fuel cell of claim 18wherein said plurality of flex circuits have at least a portion which isacid-resistant.